Treatment with PDL1 expression positive?

Hi, My name is Ina and i am writing on behalf of my dad who was diagnosed with lung cancer- adenocarcinoma 3 months ago. I live in Washington DC and my dad lives in country Georgia. Since I joined this forum, I learnt so many things, reading some of the stories gave me hope and I will be able story about my dad with positive results. Since I cannot bring my dad here in the USA, I am trying to get a second opinion on the treatment that he was given. I would appreciate very much if you give me some information and advice. After the genetics test we were told that ROS-1, ALK were negatives but PDL1 expression is positive and MSI-is High. These results mean that they cannot use targeted therapy but they can use immunotherapy with chemotherapy; Doctors advised Pembrolizumab(keytruda) 200mg+ carboplatin+ pemetrexed /every 3 weeks And with pemetrexed, we must take folic acid vitamin and B12 The treatment will be repeated every 3 weeks and until 6th cycle. I am interested in side effects too. For how long the side effects last usually? I worry that with both Chemo and Immunotherapy every 3 weeks he wont get a break practically and the side effect being severe. Thank you again.